Research On Collapsible Mechanism Of Loess Based On Granular Scale

Loess is a soil-like deposit with different levels and different particle sizes as the skeleton particles in its microstructure formed by the wind transportation and deposition in the terrestrial environment under arid and semi-arid climatic conditions since the Quaternary and undergoing a certain soil formation process.It has the characteristics of porous and weak cementation,and its particle size is mainly powder particles,followed by sticky particles.Powder and clay particles occupy a particularly important position in the loess structure,and their contents and occurrence forms directly affect the macro-mechanical properties of the loess.Therefore,to study the microstructure of the loess from the granular scale is helpful to reveal the micromechanism of the loess’ s mechanical properties.This paper mainly analyzes and studies the skeleton particles that make up loess,and some of the skeleton particles exist in the form of agglomerates,so the research objects of this article mainly include three aspects: powder particles,viscose particles,and agglomerates.Firstly,through literature research and microscopic image observation of loess,the occurrence forms of powder particles and viscose particles and the formation process of agglomerates were sorted,summarized and summarized,and four effects of viscose particles on loess structure were obtained.,Which are the effects of "filling gaps and rounding","thickening and increasing","acting as a matrix" and "forming pores".The aggregates are divided into four types and the aggregation levels of the aggregates are summarized.The lower agglomerates have higher internal strength than the agglomerates with higher aggregation levels,and the agglomerates are more stable and are not easily destroyed under mechanical action.On the contrary,the agglomerates with higher aggregation levels are weaker and more prone to damage.On this basis,the samples prepared by agglomerates/particles of different particle sizes were obtained by screening and sample preparation,and the samples prepared by different remodeling processes in the laboratory were designed to design the collapsible test and micro SEM observation methods respectively Combined,we explored the microscopic mechanism of loess collapsibility from the granular scale.The results show that the agglomerates with larger particle size have weak agglomeration and are easy to break under the same external force,and the amount of collapsing is determined by the compression of the pores between the agglomerates and the agglomerates and the agglomerates after saturation with water The conclusion of the internal pore compression is composed of two parts.Finally,the change of the location of the viscose particles inside the loess before and after collapsing and the shape change effect on the single mineral framework particles are compared and analyzed,and the internal mechanism of the loess collapsing is well revealed from the grain scale.